The present invention relates to a device for cutting continuous cigarette rods.
On cigarette manufacturing machines, at least one continuous cigarette rod is formed and fed axially and continuously through a cutting station where it is cut transversely by a cutting head into a succession of portions for supply to a follow-up, e.g. filter assembly, machine.
On known cigarette manufacturing machines, the cutting station normally comprises a tubular element--hereinafter referred to as a "counterblade"--which is coaxial with the path of the continuous cigarette rod through the cutting station, is movable back and forth in the traveling direction of the cigarette rod, is engaged, in use, in sliding manner by the cigarette rod, and is divided substantially into two integral parts by an intermediate transverse slit through which the cutting head moves during the cutting operation. In other words, just before and during the cutting operation, the counterblade moves in the traveling direction of and at the same speed as the cigarette rod, which is supported on either side of the cut by the two portions of the counterblade, so that the accuracy and neatness of the cut depends on how narrow the transverse slit is.
On most known machines, the counterblade and the cutting head are connected to the ends of respective drives, the only common feature of which is that they are so linked as to enable the counterblade to move with the cigarette rod when this is engaged by the cutting head, normally by means of a blade inclined in relation to the cigarette rod so that, during the cutting operation, the point of contact between the blade and the cigarette rod travels in the same direction and at the same speed as the rod. The fact that the counterblade and the cutting head are connected to different drives inevitably results in a lack of synchronization and, hence, the need for a relatively wide transverse slit in the counterblade.
One solution to the above drawback is proposed in French Patent Application n. 78 29 511, wherein the cutting head is mounted for rotation on a reciprocating support, which travels with the cigarette rod during the cutting operation and supports the counterblade in a fixed position.
Such a solution presents several drawbacks, mainly due to the vibration induced in the machine as a whole by the reciprocating movement of the cutting head, which is relatively heavy.